Method and machine for sewing cement bonded seams



April 1, 1947 J. P. i-*REDERICKSEN 2,418,169

METHOD AND' MACHINE- FOR SEWING CEMENT BONDED SEAMS meuf??? April l, 1947 J. P. FREDERICKSEN 2,418,169'- SEWING CEMENT BONDD SEAMS Filed July 2, 1945 2 Sheets-Sheet 2 METHOD AND MACHINE FOR Patented Apr. 1, 1947 METHOD AND MACHINE FOR SEWING CEMENT BONDED SEAMS James P. Fredericksen, Braintree, Mass., assgnor to United Shoe Machinery Corporation, Flemington, N. J., a corporation of New Jersey Application July 2, 1945, Serial No. 602,896

15 Claims.

The present invention relates to methods and machines for inserting in sole leather or other thick materials a cement-bonded seam, and more particularly that type of seam the thread in which is treated before inserting the seam with strongly adhesive material requiring the exercise of special precautions and treatments for use and having a substantially greater holding power than wax or glue compounds heretofore utilized in a similar manner.

In sewing materials of relatively marked stiliness and toughness, such as sole leather, compressed fiber, etc., it is common to employ a waxed thread- Wax is applied to the thread to lubricate, strengthen and preserve the strands and for other purposes as below explained. To wax the thread, it is treated in a bath of suitable liquid compound before entering a sewing machine proper and, in some instances, the compound is applied to the thread before the thread is wound onto the cop or spool utilized as a supply for the machine, In most cases, the wax compound has a thermoplastic nature to enable convenient storage and handling of a cop or spool with the compound in hardened condition. To soften the compound, the cop or spool is subjected to heat before being unwound in the machine. The compound impregnates the fibers of the Vthread so as to impart a greater tensile strength while the stitches are being formed and set and acts as a preservative against deteriorating action in the completed seam. The compound, when hardened in the work, also assists in sealing the stitches of the seam against entry of water or corrosive elements. To a limited extent, the compound, after hardening, resists loosening of the stitches, thus contributing to a stronger and more secure seam than is obtainable with dry, untreated thread.

The use of thread treating compounds in a sewing machine according to prior practices necessitates removal of surplus compound from the outer surface of the thread before the thread is drawnrinto the work. This is usually accomplished by carrying the thread through a stripper which fits closely and scrapes the thread free are relatively large as compared to the size of the thread, there will be many voids in the interstices between the thread bers, and the sealing action of the hardened compound will be ineffective against entry of deteriorating substances. If an attempt were made to fill the voids in the thread by sewing with a heavy coating of surplus compound on the thread, the thread as it is being led to the machine and manipulated by the stitch forming devices would have its surplus coating thrown oir by rapidly tightening and s'lackening movements of the thread, and the major part of the remaining thin layer of compoundwould be scraped away by engagement with the stitch forming devices, little or no better results being obtained in sealing action than when the surplus is removed from the thread by a stripper before reaching the sewing point. Furthermore, compound thrown off the thread would accumulate on the operating parts of the machine or be scattered over fini-shed surfaces of the work.

Treating thread employed in sewing machines with compounds composed of materials primarily .of a strongly adhesive nature is surrounded by difficulties far greater than with compounds hav` ing predominantly a lubricating character@ Not only is a compound of a strongly adhesive nature often diicult to apply in uniform quantities along the thread, but any accumulation of such compound on the working parts of the machine may soon render the machine inoperative and subject to breakage when hardening takes place. rIThe necessity for frequent cleaning of hardened compound from a sewing machine as a result of using such an adhesive more than offsets any advantages gained by combining sewing and cementing operations, it being simpler and more effective to threat the thread in a separate operation after the sewing is completed.

In order to obtain the best seam sealing action of an adhesive compound in a sewing machine, particularly with those compounds having a large proportion of highly volatile solvents providing quick-setting qualities, a thick coating of surplus compound on the thread is desirable. Accordingly. the problem of preventing surplus compound from being thrown 01T the thread between the times of application and entry into the work is much greater with quick-setting compounds than where a limited quantity, particularly of a thermoplastic nature, is utilized primarily for lubricating the thread, l

In some instances,sewing thread having a hardened resin incorporated therein has been subjected to treatment just before use with an plying a complete adhesive compound containing the solvent during sewing. With such treatment, the diculties enumerated above arise as soon as the resin softens, or the solvent is thrown oil" before it has time to act. Furthermore, the solvent in Ithe activating agent frequently is highly inflammable, a source of danger from explosion and -detrimental to health when continuously inhaled. Where it isimpossible to coniine fumes from a volatile solvent to a restricted portion of the machine, proper ventilation and removal of fumes can be obtained only by enclosing the entire machine within a hood. Such enclosure is both expensive and undesirable when frequent adjustments are required in the machine, and the accumulation of fumes Within the hood may still lead to dangerous conditions.

For these reasons, the usual practice hereto- `flore employed for inserting a cement-bonded.

venient applicator on the exposed threads of the seam. The portions of thread passing through the perforations in the workare not accessible for. treatment in this way.A The only possibility fof bringing the adhesive agent into the perforations, therefore, is through seepage along the fibers `of the thread. At best, the ends of the perr'forations vonly will be filled with cement after the operation isV completed and, with extremely thick york, Vfull advantage is never obtained in a seam `bythe addition of the adhesive agent in this way. robject of the present invention is to provide Aawmetljicd and a machine for inserting stitches, thethreadof `which is treated with a ,compound primarily of an adhesivenature to form a secure :cement-bonded seam in such a way that larger ,arnclzunts of compound Vthan heretofore considered VIl iossible during practical commercial sewing operations may khe applied and drawn with theA thread, into the perforations containing the adhesiveor other type, in which there is little opportunity for the surplus compound to become ldisplaced Vfrom the thread before being carried Linto the work, thereby preventing accumulations on the machine or elsewhere. The fullest possible benets are thus obtained from the action ,of the` compound on the seam without the usual disadvantages.

The construction of a large class of sewing machineshis such that the stitch forming devices l.Which include a work penetrating instrument act alternately first` to initiate formation of a stitch, the threads of which are inserted within a perforation introduced by the penetrating instrument, ,and then to exert a final pull on the thread after each stitch formation to cause the stitch to be set.4 During formation of each stitch while the V,thread-,is being rapidly tightened and slackened andufrictionally engaged by the stitch forming devices and the work, according'to an important .feature of the present invention, the thread is ',Iwthis'vway, afveryshortfmovement is ,imparted to the thread 'in the work'after the compound is applied, so that there is small chance of throwing off the compound or jamming the thread inthe work.

The stitch setting pull and final tension ordinarily is exerted on the thread at one side of the work to take out the slack at the other side of the work, the threads of each stitch sliding into their ultimate positions with relation to the perforation Within which the stitch is formed. lIn the method and machine of the present invention, the thread is treated at the slack thread side of the work with a surplus quantity of adhesive agentafter formation of each stitch is substantially completed and the treated thread is carried into the work just before the stitch is set. Usually in the type of machine to which the present Yinvention is illustrated as applied, movement of thread is relatively slow just before a stitch setting tension occurs, so that there is little chance of throwing or scraping off surplus amounts of compound with which the thread is coated before being drawn into the work. A

large proportion of the surplus compound will therefore be drawn with the thread into the substance of thework through the perforation, insuring a secure bond of the thread'with the inner surfaces of the perforation when the compound hardens. Preferably, a limited length only of thread is treated at a time with the compound so as to avoid the possibility of any portion of the treated thread coming into contact with the stitch forming devices or other operating parts of the machine. The untreated portion of the thread in each stitch may therefore be manipulated by the stitch forming devices of the machine without danger of scraping off the compound, thus insuring proper completion of stitch formation and enabling the use of highly adhesive synthetic compounds on the thread.

Where there is a relatively large surplus of adhesive compoundemployed, accumulations may be produced in the seam at one or both ends of 'each of the perforations in the work after the stitch is set. If the compound is of the proper consistency and is drawn entirely through the -'perforation with the thread in the proper manner to produceregular accumulations at the ends Vof the perforations, the stitches of the seam will will be anchored at the ends of each perforation with rounded knobs of cement, thus adding to the tenacity and durability of the seam and providing tightseals for the outer ends of the perforations. If a compound is used which contractsupon hardening, the Vwill be enhancev correspondingly.

Other features of the invention consistV in the combinations and arrangements lof essential steps in the method and of devices and parts in the machine as hereinafter described and claimed and the advantages to be obtained thereby will readily be understood from the following descriptionV taken in connection with the accompanying drawings, in which Fig. 1 is a fragmentary view in rightside gelevation of the upper portion of a welt shoe sewing machine embodying improvements' of the `present invention and showing `a, partial section of a welt shoe in operating position;

Fig. 2 is a fragmentary View on an enlarged scale taken at one side of a seam sewn on the Vmachine of Fig. l;l

Fig. 3 isa partly sectional view at the other Sie@ Ofi-theseam: r Y MillFig,fljnisa view in side .elevation on an enlarged scale, partly broken away, of the forwardporv tightness of the seam tion of the sewing machine illustrated in Fig. 1;- Fig. 5 is a sectional detail view of the pressure system and reservoir for the thread treating means employed with the machine of Fig. 1,

taken along the line V-V of Fig. 4;

Fig. 6 is a detail vie-w in front elevation on a further enlarged scale of the channel guide for the machine of Fig. l; i

Fig. 'l is a detail View in left side elevation of the channel guide.

Fig. 8 is a detail plan view, indicating the operation of the stitch forming devices and thread treating means in the machine while the needle is extending through the work during the operation of the looper and thread linger;

Fig. 9 is a similar view of the same parts while the needle is being retracted and a coating of an adhesive agent is being applied to the thread; and

Fig. 10 is a similar View of the same parts, taken while the stitch formed in Fig. 9 is being tightened.

The machine illustrated in the drawings is adapted for inserting an inseam in a shoe, the threads in the stitches of which are treated with a relatively thick surplus coating of an adhesive agent having a peculiar afnity for both the thread employed and the substance of the work operated upon to enable easy and prompt absorption thereby. The adhesive employed is composed of a synthetic resin and a highly volatile solvent to facilitate quick hardening action and is provided as a compound the proportion of the constituents in which depends upon the type of resins employed. Useful resins for such purposes include cellulose nitrates, acetates, phenolic condensates, vinylites or other similar substances.

f Compounds of such resins, particularly when applied in surplus quantities, increase the rigidity of the parts to which they are applied and provide a bond of substantially greater strength than that obtainable with the natural adhesives or where reliance is made wholly on a wax or resin applied to lubricate the thread before entering a sewing machine. The term adhesive agent hereinafter used is intended to include any of these materials and solvents either when applied together or separately to the thread.

Except as hereinafter pointed out, various parts `of the machine illustrated in the drawings are constructed, arranged and operated in the saine manner as in the machine disclosed in prior United States Letters Patent No. 2,041,945, granted May 2.6, 1936; No. 2,219,933, granted October 29, 1940; and No. 2,220,112, granted November 5, 1940, all in the name of Alfred R. Morrill. That machine acts during sewing operations to draw successive loops of thread 4 through the upstanding rib of an insole 6, the marginal portion of a lasted shoe upper 8 and a welt I0 to form chain stitches. The operating devices of the machine comprise a curved hook needle l2, an awl i3, a looper I4, a thread arm or ringer l, a stitch setting take-up i8, a tension wheel i9, a welt guide 20, a channel guide 22 and a back rest 2li. These devices are arranged and actuated both to insert stitches passing through perforations formed by the awl and needle in the parts and to feed the work, the needle passing through the parts and emerging from the opposite side of the between substance inside of the channel during the formation of each stitch, as illustrated in Fig. 8. The channel guide supports the sewing rib on the insole 6 during penetration of the needle and enables the substance of the shoe parts operated upon to be compressed together rmly with the stitches inserted at the desiredlocation while the welt guide urges the welt against the upper at the opposite side from the channel guide. As soon as the needle emerges from the work, the hooked end is surrounded by a loop of thread which is then retracted with the needle, as in Figs. 9 and 10, the needle withdrawing sufficiently from the opposite side of the work to tighten the thread and to take out from be tween the stitch being formed and the previous one the slack thread provided by the thread nger i6.

In machines of the shoe sewing type, the operation of the devices which act directly on the thread to form stitches at speeds of operation commonly employed in present-day use cause the thread to be tightened and loosened so rapidly that it is impossible to maintain a, surplus coating of liquid or semisolid compound on the thread during formation of stitches. The greatest amount of compound which ordinarily can be carried into a seam with the thread in such machines is that which the thread is able to absorb within the interstices between its fibers, the surplus usually being wiped off the outer surfaces of the thread before reaching the stitch forming devices.

The usual thread treating apparatus comprises a wax pot similar to that indicated at .2li in Fig. 1 of the drawings. The thread is led from a supply reel 28 downwardly through liquied wax compound in the pot and upwardly through a guide comprising a stripper 30 acting to wipe olf the surplus from the surface of the thread. If

the wax compound is liquified by -heat in the pot 25, all of the thread engaging and stitch forming devices coming into contact with the thread are heated in the machine to prevent the compound from becoming hardened in advance of stitch formation. Thus, with the limited quantity of compound absorbed by the thread, some benefit is obtained by way of increased strength in the thread and some preservative action may follow in subsequent use of the work if the compound is of the proper nature. However, the lubricating,

. sealing and bonding action of the thread in the work is substantially reduced from possible optimum conditions present with the use of .a surplus of compound, effectiveness of the compound in these respects being determined by the extent to which the thread is compressed and the absorbed compound is squeezed to the surface of the thread While passing through the work during stitch formation. If a high degree of thread compression occurs in the Work, some of the absorbed compound will be forced out, tending to fill the voids in the perforation within which a stitch is being formed. To this same extent, the threads will be bonded to the inner surfaces of the perforation in the work, but the strength of the bond will depend upon the degree of hardness and tenacity of the basic resin in the compound. Also, with soft, low-tenacity wax type resins, the problem of removing accumulations of hardened compound on the moving parts of the machine is of relatively simple solution. Foi` these reasons, there has never been a Wide-spread use of harder, more tenacious resins of a synthetic nature in sewing machines, particularly of the shoe sewing type. Where there is a need for synthetic resin cement bonded seams, the exposed threads have heretofore been treated according to commercial practice after the seams are inserted. By treating the exposed threads only, of a com- 7' pleted seam, a secure bond is obtained betweenw the threads and the outer surfaces of thev work, but the bond between the threads and the inner surfaces of the perforation in which each; stitch is formed is muchr weaker than where the compound is drawn into the perforation with the thread.

In the illustrated embodiment of the invention, all of the benefits in the way of increased strength in the thread, and preservative, sealing and bonding actions are obtained with a synthetic resin adhesive compound having a. high degree of hardness and tenacity after solidification without the disadvantages ordinarily resulting from the use of a surplus quantity of liquefied thread treating compound on a sewing thread employed in a high-speed sewing machine. These results are obtained in the present machine by utilizing apparatus for treating with compound onlya portion of the thread left slack by the action of the thread ilnger Iii between the stitch being formed and the previous one, the thread operated upon by the stitch forming devices being maintained free of adhesive compound at least until the formation of each stitch is substantially completed.

Referring more particularly to Figs. 8, 9 and 10 of the drawings, a step-by-step illustration of the operation of theneedle i2 and the looper Hl during formation of each stitch is illustrated. Fig. 8 shows also the action of the thread nger in providing slack thread. After the previously formed stitch has been set in the work by the application of a stitch setting tension to the thread by the take-up while a loop of thread surrounds the shank of the needle engaging the work, the looper moves the thread into contact with the thread nger so as to hold aside a limited quantity of thread and then to surround the needle with a loop of thread along its shank and above its hook. As the needle starts to retract, the loop of thread formed on the shank of the needleV is carried into the needle hook and the threaded needle, together with the loop, is retracted through the work, as in Fig. 9. As soon as the threaded needle hook begins to enter the work during the retracting stroke of the needle,

the thread finger moves to release the quantity of thread withheld to form slack between the previous stitch and the stitch being formed. It is at this instant that a surplus quantity of liquid adhesive compound is applied to the thread at a position in close proximity to the point oi entry of the needle hook into the perforation in the Work. 1n this way, contact of the adhesive-agent with the needle is prevented. rlhe portion of the thread to which the compound is applied is of sufficient length to enable a substantialV amount of compound to be carried with the thread entirely through the thickness of the work during the retracting stroke of the needle, and the time of application of the compound is extended to insure that this result is obtained. After being retracted from the work, the needle continues to pull the loop of thread held in its hook andl eX'- tending through a perforation in the work until all the looseness is entirely taken out of the thread at the slack-thread side of the work opposite that to which the thread is pulled and on which the looper and thread iinger are located and, in so doing, some oi the surplus compound is scraped from the thread, resulting ina bead like accumulation 32. In this way, it is necessary to treat only a limited length. of thread between stitches at the slack` thread'. side of the alliance:

work, leaving a remaining length of thread be# tween stitches substantially free from accumulations or surplus quantities of adhesive compound. After the compound has hardened, the

L beads 32 form plugs for the ends of the perforations through which the stitches pass, the remaining lengths of thread between. perforations being free of hardened compound.

In withdrawing from the work with each loop of thread, as in Fig. 10, the needle usually pulls an amount of thread with it greater than required at the needle side of the Work for the completion of the succeeding stitch. Also, While theneedle is withdrawn, the work is fed the length of a stitch by the awl which partially penetrates the Work to form an indentation, such as that indicated at 3Q, in line with the path of the needle, the feeding movement pulling additional thread through the work. The needle thereafter completes the perforation started by the awl and emerges from the opposite side to a position where it may again be looped. Itis while the needle is in this position that the loop in the stitch previously formed is pulled through he perforation and tightened by the take-up about the shank of the needle. Some of the thread in the loop is returned through the previous perforation at this time. During the return movement oi the thread in the loop through the perforation, some of the surplus compound on the thread at the needle side of theV work is scraped off as a bead t@ at the end of the perforation nearest the loop, thus supplying an accumulation for a hardened plug on the thread at each end of the perforation when the com.

pound solidics. The application of the compound is suitably regulated to reduce to a minimum the amount on the thread treated between stitches at the needle side of the work so that the flexibility of the seam will not be substantially reduced.

To treat thread in the manner outlined at the slack thread side of the Work only, a pressure system for the adhesive is provided. This system has a vent di) through the channel guide 22 of the illustrated machine and is provided with a compound conducting passage 38. The vent 4l] is directed toward the needle path and opens into close proximity to the course taken by the thread while being drawn through a perforation in the' work by the needle. The passage St is connected to the pressure system containing the adhesive compound, through an inlet i2 onthe. channel guide, a iiexible conductor dit, and a measuringV pump which constitutes the pressure system, the pump receiving its supply of compound from a reservoir it bolted at t3 to the right side of the sewing machine frame. The measuring pump has a central cylinder 5@ provided with a valved side inlet 52 and a valved outlet 5ft connected to the conductor Mi. Within the cylinder 50 is a tappet actuated'V piston 56 yieltingly maintained in raised position by a coil spring 5,8 surrounding the piston and a sleeve-like guide on the cylinder between a shoulder on the cylinder and a disk-shaped head on the piston.

To actuaterthe measuring pump, the piston ls engaged by a rocker arm da projecting radially from a fulcrum stud G2 for the take-up I8. The arrangement is such that the rocker arm engages a fiat disk-shaped portion of the piston while the take-up is giving up thread to thevneedle, and the quantity of compound projected through the vent in the channel guide may becontrolledi by adjusting a thumbscrew 64 threaded Withinv a. lug at one side of the reservoir 46 with its lower end acting as a stop for upward movement of the piston. f

To close the reservoir 46 and prevent evaporation of solvent from the liquiiied compound, a cover 66 is hinged at its rearward end to the reservoir to seal its upper opening in a suitable manner, the use oi a gasket or other hermetically sealing means being dependent upon the type of compound and solvent employed.

With the use of certain types of adhesive compounds, it is desirable to provide a preliminary treatment for the thread. Where such treatment is necessary, the wax pot 26 is used for this purpose. Such treatment consists of oil or water removal by passing the thread through suitable reagents within the wax pot or by sub- `jecting the thread to heat only to drive out excessive volatile constituents or otherwise to condition the thread. Ii the pot is used for subjecting the thread to heat, suitable ventilation means are desirable, including devices for producing a forced draft or air conditioning equipment,

In performing the steps of the method followed and in the embodiment of the machine above described, it has been presumed that a synthetic resin compound which is complete in itself and in a liquied condition may be applied directly to the thread. In certain of its aspects, however, the invention is applicable with advantage to methods and machines in which the thread is treated, before coming into contact with the stitch forming devices, with one or more separate constituents of an adhesive compound which do not produce an objectionable condition in the thread from a standpoint oi manipulation in the machine, the remaining constituents A being applied to activate the compound at the slack thread side of the work in the manner described. In carrying out the method of separate activation of compound already applied to the thread, the wax pot 26 is utilized.

The invention herein disclosed and claimed is similar in certain respects to that in an application for United States Letters Patent, Serial No. 602,854, led of even date herewith in the name of Clyde L. Knott, in which plugs containing a plastic material are employed to cement serially connected loops of thread to the inner surfaces of perforations through which the loops pass.

The nature and scope of the invention having been set forth and a particular embodiment of the invention having been described, what is claimed is:

1. The method of inserting a seam with cement bonded stitches including the steps of perforating the work, pulling thread from one side of the work through perforations successively to the other side, and providing slack thread between each stitch being formed and the previous one, which comprises treating the thread between perforations while slack with an adhesive agent.

2. The method of inserting aseam with cement bonded stitches including the steps of perforating the work, pulling thread from one side of the work through perforations successively to the other side, and providing slack thread between each stitch being formed and the previous one, which comprises treating the thread between perforations while slack with an adhesive agent, and pulling thread through a perforation to take out the slack in the thread and to carry l0 the 'adhesive agent' into the perforation with the thread.

3. The method of inserting a seam with cement bonded stitches including the steps of perforating the work, pulling thread from one side of the work through perforations successively to the other side, and providing slack thread between each stitch being formed and the previous one, which comprises treating a limited length lof thread while slack between stitches with an adhesive agent at a position spaced from theprevious stitch sufficiently to cause the adhesive agent to be carried substantially through the perforation when the slack is taken out.

4. The method of inserting a seam with cement bonded stitches including the steps of perforating the work, pulling thread from one side of the Work through periorations successively -to` the other side, and providing slack thread between each stitch being formed and the previous one, which comprises treating a limited length of thread while slack between stitches with adhesive agent at a position spaced from the previous stitch suiiiciently to cause the adhesive agent to be carried into the perforation when the slack is taken out and with suicient surplus quantity of adhesive agent to cause it to accumulate substantially at the end of the perforation into which the slack thread is drawn.

5. The method of inserting a seam with cement bonded stitches, which comprises perforating the work, providing slack thread between a stitch already formed and a stitch being formed, pulling that slack thread from one side of the work to the other side through a perforation to tighten the stitch and during such pulling applying an adhesive agent to the thread at the slack thread side of the work.

6. The method of inserting a seam with cement bonded stitches, which comprises perforating the work, providing slack thread between a stitch already formed and a stitch being formed, pulling that slack thread from one side of the work to the other side through a perforation t0 tighten the stitch and during such pulling applying an adhesive agent to the thread at the slack thread side of the work, and finally applying a stitch setting tension to the thread.

7. The method of inserting a seam with cement bonded stitches, including the steps of' perforating the work, drawing loops of thread to form.

stitches successively into the perforations, and pulling a loop from one side of the work through each perforation to take out slack thread at the other side of the work between each stitch being formed and the previous stitch, which comprises coating the thread along a slack portion of the thread with an adhesive agent while pulling the loop from the perforation to cause the adhesive agent to be carried into the perforation with the thread, and pulling one side of the loop back through the perforation to cause a surplus quantity of the adhesive agent, carried through the perforation with the thread while pulling the loop, to accumulate at the end of the perforation from which the loop is pulled.

8. A machine for inserting `a cement bonded seam, having devices for manipulating thread to form stitches successively and for pulling thread from a perforation at one side of the work to take out slack from between the stitch being formed and the previous stitch at the other side of the work and to set each stitch, in combination with means for treating the thread between stitches with an adhesive agent at the slack 1i1 .thread side of the work to cause the adhesive agent to be drawn into a perforation while the aslackineachstitchis being 'pulled out.

9. Av machine for inserting a cement bonded seam, having devices for manipulating thread to 1:

form stitches successively and for pulling thread :from'a perforation at one side of the work to takeout slack from between the stitch being Vformed and the previous stitch at the other side .of the work to set each stitch, in combination .with means for treating a limited length of 4thread Ybetween stitches at the slack thread side of the work with an adhesive agent while pulling the thread to take out the slack, the treating operation being so extended that the treated length of thread will be drawn substantially fthroughthe Vwork before each stitch is set.

10. VA machine for inserting a cement bonded chain-stitch seam having a hook needle, a looper, a thread finger acting between the last formed 'stitch and the looper to provide slack thread for the-needle, and other stitch forming devices for 'pulling thread from a perforation at one .side of the work to take out the slack provided :by the `thread linger at the other side of the work Yand toset -each stitch, in combination with means for treating the thread along that portion acted upon by the thread finger with an adhesive agent to cause the adhesive agent to be drawn into a perforationV before each stitch is set.

11. A Vmachine for inserting a cement bonded chain-stitch seam, 'having a hook needle, a looper, a thread finger acting between the last formed stitch andthe looper to provide slack thread for the needle, and 4other stitch forming devices for pulling thread from a perforation at one side of the Work to take out the slack provided by the thread finger at the other side of the Work and to set each stitch, in combination with means ofthe work Yto take out the slack provided by the thread nger at the other vside of the work and ntorseiwe'achrstitch,in combinaiton Vwith-meansfcr .treating ,the-thread along that portion acted upon by the thread nger, comprising a pressure system containing a liquid adhesive agent and having a vent directed against the path of the needle, and devices for causing a limited quantity of adhesive agent to be projected through the vent against the thread carried by the needle during lits retracting stroke only.

13. A machine for inserting a cement bonded chain-stitch steam, having a curved hook needle, a looper, a thread finger acting between the lastformed stitch and the looper to provide slack Ythread for the needle, a channel guide and other stitch forming devices for pulling thread through a perforation at one side of the work to take out the slack provided by the thread finger.. at the other side of the work and to set each stitch, in combination with means for treating the thread along that portion thereof engaged by the thread nger, comprising a pressure system containing an adhesive agent, a passage for the adhesive agent to the channel guide, a vent in the channel guide directed toward the needle path, and devices for projecting a quantity of the adhesive agent through the vent against the thread carried by the needle during its retracting stroke.

14. The method of inserting a seam with cement bonded stitches including the steps of perforating the work, pulling thread from one side of thework through perforations successively to the other side, and providing slack along a portion of the thread in the stitch being formed at the side of the work opposite that to which the thread is pulled1 which comprises the additional step of treating the thread along said slack portion with an adhesive agent before all the looseness is taken out.

15. A machine for inserting a cement bonded seam, having devices for manipulating thread to form stitches successively and for pulling thread to one side of the work through a perforation in the 'work to take out slack in the thread at the other side of the work and to set .each stitch, in combination with means for treating the thread withan adhesive agent at the slack thread side of the work to cause the Vadhesive agent to be drawn into a perforation while the slack'thlead in each stitch is being pulled out.

JAMES P. IF'REIDlElRICKSEN. 

